# BR-CIUS-PT-25

Source: https://xmlvalid.com/rules/BR-CIUS-PT-25

> A Credit Note shall contain the Preceding Invoice Reference (BG-3).

- Level: error
- Rule sets: CIUS-PT rules (Portugal, UBL) 2.1.1
- Context: `//ubl:Invoice | //cn:CreditNote`
- Test: `exists(//cn:CreditNote) and not(cac:BillingReference)`

Validate a document against these rules: https://xmlvalid.com/validate